Element basket for heat exchanger



April 18, 1967 KRUMM ET AL ELEMENT BASKET FOR HEAT EXCHANGER OriginalFiled Aug., 25, 1964 United States Patent 3,314,472 ELEMENT BASKET F ORHEAT EXCHAN GER Eugene D. Krurnm and Norman Casagrande, Wellsville,N.Y., assignors to The Air Preheater Company Inc., a corporation ofDelaware Continuation of application Ser. No. 391,841, Aug. 25, 1964.This application Apr. 6, 1966, Ser. No. 540,778 7 Claims. (Cl. 16510)ABSTRACT OF THE DISCLOSURE A matrix for a rotary regenerative heatexchanger in which a series of laterally adjacent plates are biasedtogether by a laterally acting spring means in a manner that precludestheir relative movement and thus prema ture failure from abrasion orvibratory strain.

This is a continuation of application Ser. No. 391,841, filed Aug. 25,1964, and now abandoned.

In rotary regenerative heat exchange apparatus a mass of heat exchangematerial which is commonly comprised of a packed series of elementplates is first positioned in a hot gas passageway to absorb heat from astream of hot gases and then as the plates become heated they are movedinto a spaced passageway for cooler air where the heated plates transmittheir heat to cooler air or other gases passing therethrough.

The apparatus is usually disposed about a vertical axis such that thereis imparted to each element plate substantial stability wherebydetrimental movement or vibration of each element plate is possible onlywhen a blast of high pressure cleaning air or steam is blown through thespacing between element plates to remove objectionable depositstherefrom. If however the apparatus is disposed about a horizontal axis,each increment in the rotation of the rotor causes the element plates tobe agitated an amount which is dependent upon the tightness with whichthey are packed in the apparatus.

Consequently, a serious condition resolves around the fracture ofelement plates by failure from fatigue thatis caused by their nearlycontinuous agitation. To alleviate the problems associated with thiscondition, bundles of element plates are frequently packed tightly inopen ended bundles before being assembled according to a preconceivedplan into the heat exchange apparatus. Although packed tightly whenassembled, corrosion and erosion of the element plates during operationof the apparatus tends to weaken and loosen them until the normalrotation of the rotor agitates them suflicient to bring about theirdestruction.

The present invention therefore contemplates an arrangement whereby thebundles of element plates are held in a continuously tight relationship,even after they have been seriously worn away by the forces of corrosionand erosion, so as to substantially preclude their destruction fromfatigue.

The invention may be more readily understood when reviewed inconjunction with the accompanying drawings in which:

FIGURE 1 is a sectional view of a rotary regenerative heat exchangerembodying the invention,

FIGURE 2 is a view of the invention as seen from line 22 of FIGURE 1,

FIGURE 3 is a perspective view of a basket having a single curvedloading plate,

FIGURE 4 is an enlarged sectional view of an element basket havingloading plates at opposite ends thereof.

As illustrated in the drawing the heat exchange apparatus comprisesessentially a housing enclosing a rotor 12 containing a mass of heatexchange material 14 that is contacted by a stream of hot gases enteringthe housing through an inlet duct 16 and exhausted through an outletduct 18 after having traversed the heat exchange material in thecompartments therebetween. Cool air or other cool gas entering thehousing through an inlet 22 is exhausted through an outlet duct 24-after having traversed the heat exchange material lying in thecompartment therebetween. While the gases are being directed throughtheir respective passageways the rotor 12 is being rotated about itsaxis by drive means 20 in order that each portion of heat exchangeelement contained therein may be alternately subjected to the hot andcool gas.

The heat exchange material carried by the rotor comprises a mass of heatabsorbent plates 26 formed with projections that provide flowpassageways therebetween for the flow of hot and cool gas. The platesare assembled in an orderly array and positioned in a metallic basketthat firmly holds the plates in a predetermined relationship in orderthat they may be easily handled as an integral element mass whenarranged in the rotor of a heat exchanger.

Each basket essentially comprises a pair of spaced end. plates heldtogether by side or tension straps. More particularly the end platescomprise a pair of curved spring plates 28 and 29, or a single curvedspring plate 28 and a plane plate 27 between which are packed the heatabsorbent plates 26. The end plates are held together tightly by tensionstraps 32 in order that the element plates 26 are similarly held in atight relation. The tension straps 32 are preferably flanged along thelongitudinal edge lying at the edge of a basket assembly to provide aretaining surface for the heat absorbent plates 26 carried within thebasket.

In making a basket assembly a plane plate 27 or a formed plate 2 isfirst positioned on a suitable working surface. If a formed plate 29 isto be used it is placed on the working surface with its convex surfacefacing upward. Straps 32 are then secured to a pair'of opposing straightedges of said plate to provide in efiect an openended rack onto whichmay be stacked a quantity of formed plates 26. When a predeterminedquantity of plates has been thus assembled on the open rack, a secondconvex spring plate is positioned upon the stacked plates 26 with itsconvex side facing downward and in abutment with the topmost plate ofthe assembly. A compressive force is then applied to the entire bundleassembly sufficient to cause the spring plates to flex and theundulations or other formations of the plates 26 to be compressedsufiicient to enable them to lie in a tightly abutting relationship.

A compressive force of from 8 to 12 pounds per square inch appliednormal to the plane of the assembled plates is usually consideredadequate to bring all plates into abutment as desired when applied to atype of undulated element plates as illustrated. However, more or lessforce may readily be applied to plate assemblies of various stiffness toproduce the desired degree of element packing.

While the compressive force is still being applied to the plateassembly, side straps 32 are welded to the straight edges of the upperspring plates 28. After the side straps have been bonded integrally tothe sides of the plate 28, the compressive force is released to permitthe normal expansive force of the corrugated element plates incombination with the normal expansive force of the somewhat compressedspring plates 28 and 29 to hold the element plates 26 in a permanentlytight relationship.

After a set of element plates has been in service for some time theremay be a tendency for the plates to corrode and erode away due to theirbeing in continuous contact with corrosive dust laden gas. When suchconditions obtain and the plates thus begin to occupy less space withintheir particular basket assembly, the spring plates 23 and 29 expand tooccupy more space in order that the element plates 26 may be held atsubstantially the same degree of tightness throughout long periods ofoperation.

Accordingly, the element plates will be held continuously tight androtation of the rotor about its axis, even if disposed horizontally,will not cause the element plates to shift or move relative one toanother. Moreover steam or air blown into the open ends of an assembledmass of plates to remove deposits of dust therefrom will not induce anyperceptible vibrational effect upon them and the destruction of platesdue to fatigue failure is substantially eliminated.

Thus, While the invention has been described with reference to theembodiment illustrated in the drawing, it is evident that numerouschanges may be made without departing from the spirit of the inventionand it is accordingly intended that all matter contained in the abovedescription or shown in the accompanying drawings shall be interpretedas illustrative and not in a limiting sense.

We claim:

1. Rotary regenerative heat exchange apparatus having a rotor includinga central rotor post and a concentric rotor shell joined by radialpartitions to provide a series of sectorial compartments therebetween, aplurality of heat absorbent element bundles carried in the compart mentsof the rotor, said element bundles each comprising a plurality ofstacked element plates, a spring loading means laterally abutting eachbundle of stacked plates, and means combining the loading means with theelement bundles to permit the spring action of said loading means tomaintain the plates in a continuously compressed relation.

2. Rotary regenerative heat exchange apparatus having a rotor includinga central rotor post and a concentric rotor shell joined by a series ofradial partitions to provide a series of sectorial compartmentstherebetween, a housing surrounding the rotor having inlet and outletports adjacent spaced ends of the rotor adapted to simultaneously directa heating fluid and a fluid to be heated through spaced compartments ofthe rotor, means for rotating the rotor about its axis, bundles of heatabsorbent element packed in the compartments of the rotor, said bundleseach comprising a plurality of stacked plates having flow passagewaystherethrough for the flow of the heating fluid and the fluid to beheated, a spring loading means adjacent each element bundle, and tensionmeans combining each spring loading means with the element plates ofeach element bundle whereby the plates are held continuously tight intheir predetermined relationship.

3. Rotary regenerative heat exchange apparatus having a rotor includinga central rotor post and a concentric rotor shell joined by a series ofradial partitions to provide a series of sectorial compartmentstherebetween, a 6

housing surrounding the rotor having inlet and outlet ports adjacentspaced ends of the rotor adapted to simultaneously direct a heatingfluid and a fluid to be heated through spaced compartments of the rotor,means for rotating the rotor about its axis, bundles of heat absorbentelement packed in the compartments of the rotor each comprising aplurality of stacked element plateshaving flow passageways therethroughfor the flow of the heating fluid and the fluid to be heated, a curved.loading plate adjacent each end of the element bundle, and means joiningthe curved loading plates at spaced ends of the element bundle wherebyintervening element plates are held in a continuously tightrelationship.

4. Rotary regenerative heat exchange apparatus having a rotor includinga central rotor post and a concentric rotor shell joined by a series ofradial partitions to provide a series of sectorial compartmentstherebetween, a housing surrounding the rotor having inlet and outletports adjacent spaced ends of the rotor adapted to simultaneously directa heating fluid and a fluid to be heated through spaced compartments ofthe rotor, means for rotating the rotor about its axis, bundles of heat:absorbent element packed in the compartments of the rotor comprisingstacked element plates having passageways therebetween for the flow ofthe heating fluid and the fluid to be heated, spring loading means atthe ends of each bundle, and a strap means affixed at opposite endsthereof to said spring loading means to provide an enclosure for thestacked element plates.

5. Rotary regenerative heat exchange apparatus as defined in claim 4wherein said strap means lying adjacent the ends of said bundles of heatabsorbent element are provided with lateral flanges that overlap the endedges of said element plates to preclude their longitudinal movementwithin the bundle.

6. An element bundle for a heat exchanger comprising a plurality ofstacked element plates, curved loading means abutting each bundle ofstacked element plates, and means combining the spring loading meanswith the ele ment bundle to permit the spring action of said loadingmeans to maintain the element plates in a continuously compressedrelation.

7. An element bundle for a heat exchanger comprising stacked elementplates having passageways therebetween for the flow of a heating fluidand a fluid to be heated, curved spring loading means laterally abuttingsaid bundle, and means aflixed to said spring loading means to providean enclosure substantially normal to said passageways for the stackedelement plates that maintains the element plates in a continuouslycompressed relation.

References Cited by the Examiner UNITED STATES PATENTS 2,579,212 12/1951Stevens et al. 10 3,191,666 6/1965 Brandt 165-9 X ROBERT A. OLEARY,Primary Examiner.

M. A. ANTONAKAS, Assistant Examiner.

6. AN ELEMENT BUNDLE FOR A HEAT EXCHANGER COMPRISING A PLURALITY OF STACKED ELEMENT PLATES, CURVED LOADING MEANS ABUTTING EACH BUNDLE OF STACKED ELEMENT PLATES, AND MEANS COMBINING THE SPRING LOADING MEANS WITH THE ELEMENT BUNDLE TO PERMIT THE SPRING ACTION OF SAID LOADING MEANS TO MAINTAIN THE ELEMENT PLATES IN A CONTINUOUSLY COMPRESSED RELATION. 